SINAD, an acronym for "signal + noise + distortion to noise + distortion ratio", is the measure of audio output signal quality for a given receiver audio power output level. Instruments indicating SINAD are used extensively, for example, in evaluating radio receiver selectivity by measuring the signal attenuation at various frequencies offset from the tuned frequency. Selectivity measurements using a SINAD method has been adopted as the standard method procedure described in IEEE Standard 184-1969, Test Procedure for Frequency-Modulated Mobile Communication Receivers, in use in the United States and throughout the world.